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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / July 2005

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Cranking engine with coil disconnected

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pcalvert@rocketmail.com - 29 Jul 2005 07:47 GMT
I have a little car maintenance book that suggests turning over the
engine (for about 30 seconds) with the spark coil disconnected right
after changing the oil.  The idea is to make sure the oil filter is
soaked/full, and the oil is flowing, before allowing the engine to turn
over on its own.  I suppose it might also be a good idea to do this if
a car has been sitting in storage for a long time.

Good idea?  Bad idea?  It sounds like a good idea to me, but I seem to
recall reading somewhere that doing this could possibly damage the
ignition system.  Perhaps this is an idea that was only good back in
the days before electronic ignition?

For what it's worth, I have used this idea a few times without any
(apparent) problem.  But I don't want to continue to do this if it's a
bad idea.

Phil
lugnut - 29 Jul 2005 13:21 GMT
>I have a little car maintenance book that suggests turning over the
>engine (for about 30 seconds) with the spark coil disconnected right
[quoted text clipped - 13 lines]
>
>Phil

Not worth the effort.  I have never seen this recommended in
any manufacturer's service literature.  If you drain and
change the oil and filter with the engine warm as you
should, everything in there that needs oil still has a
coating of oil sufficient to protect it well beyond the 5 or
6 seconds needed to restore the flow of oil after the engine
starts.  Removing the coil wire and cranking the engine with
an open coil tower is a good way to start a carbon track
which later results in failure.  If you still choose to do
this, disconnect the primary power to the coil - not the
secondary.  On an EFI engine, this may generate a fault code
for you to track down.

It is a good idea to prime or prelube a freshly built engine
or one which has been inactive for a very long time.  This
should be done with the distributor removed and the oil pump
driven by a healthy drill and an adapter for the purpose.

Lugnut
Don Stauffer - 29 Jul 2005 14:39 GMT
>>I have a little car maintenance book that suggests turning over the
>>engine (for about 30 seconds) with the spark coil disconnected right
[quoted text clipped - 33 lines]
>
> Lugnut

And, oil wets metal.  Some ads for these pre-oilers claim oil drains
completely away from bearing surfaces when car is not running.
Actually, it is hard to get bearing surfaces completely clean of oil.
Oil stays there a LONG time.  Now, this is just a film, and will not
support heavy pressure of high speed running, but as long as you do not
start car at full throttle, pre-oiling is not really necessary.

If the engine has sat a year or so without running, that is something else.
William R. Watt - 29 Jul 2005 15:07 GMT
>...everything in there that needs oil still has a
>> coating of oil sufficient to protect it well beyond the 5 or
>> 6 seconds needed to restore the flow of oil after the engine
>> starts.

They intentionaly use oils that stick to metal.  :)

In the early days of the industrial revolution machines were lubricated
with rapeseed oil because it would cling to metal. (Canola oil is a
variety of rapeseed oil developed by selective breeding to reduce some
unhealthy fats and make it the second healthiest eating oil after olive.)

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ray - 29 Jul 2005 18:26 GMT
> It is a good idea to prime or prelube a freshly built engine
> or one which has been inactive for a very long time.  This
> should be done with the distributor removed and the oil pump
> driven by a healthy drill and an adapter for the purpose.
>
> Lugnut

funny story...we were priming my Camaro engine on the stand and forgot
to plug the oil pressure gauge fitting.  Dunno the PSI, but fortunately
my garage has flourescent lights that didn't seem to mind being sprayed
with a 6' high oil fountain.

Ray
ray - 29 Jul 2005 14:32 GMT
> I have a little car maintenance book that suggests turning over the
> engine (for about 30 seconds) with the spark coil disconnected right
[quoted text clipped - 13 lines]
>
> Phil

Overkill.  What I do is fill the oil filter (if possible) when
reinstalling it.  Minimizes the time spent at 0psi without needing to
disconnect and monkey with the ignition.

If you're going to do it, I'd try disconnecting the distributor input
wires instead - no juice in = no stress on the coil and no chance of
arcing high voltage inside the cap.  Or ground the coil wire.  It's not
practical on most newer cars - my TA has 8 coils and no distributor...
I'd have to ground 8 coils.

My thought is most people don't bother doing ANYTHING when they bother
changing the oil and your average engine still makes 100,000+ miles...
so I'm sure it's overkill.

Ray
pcalvert@rocketmail.com - 30 Jul 2005 00:37 GMT
Thanks for all the advice.  I probably won't bother to do it when I
change the oil.  I'd fill the oil filter with oil if I could, but in
many cases the filter is horizontal, which makes doing that basically
impossible.

I do have a car that hasn't been driven in 9 to 12 months.  It has been
sitting less than a year, and I may have started the engine and ran it
for a few minutes once, but I don't remember how long ago that was.  It
has definitely been sitting for at least six months, though.  So I'd
rather not suddenly shock the engine by getting in and starting it up
in the normal way.

Would it be okay to crank the engine for about thirty seconds with the
coil completely disconnected?  By "completely," I mean that I will pull
off the heavy-duty wire that goes to the distributor *and* I will
disconnect the wires that supply the 12V to the coil's primary side.

Phil
William R. Watt - 30 Jul 2005 01:06 GMT
> Thanks for all the advice.  I probably won't bother to do it when I
> change the oil.  I'd fill the oil filter with oil if I could, but in
[quoted text clipped - 12 lines]
> off the heavy-duty wire that goes to the distributor *and* I will
> disconnect the wires that supply the 12V to the coil's primary side.

You can remove the spark plugs and squirt some motor oil directly into the
cylinders before trying to start the engine. When my car has been sitting
for a few days I crank the engine over a few times without pressing down
on the gas pedal. The engine doesn't fire. I wait a second or two imaging
oil is running down the cylinder walls and other helpful places and doing
the engine good, then start the engine. I don't know if it does any good,
but it does no harm.

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Proctologically Violated©® - 30 Jul 2005 02:07 GMT
If you disconnect the 12V wires going to the coil, you shouldn't have to do
anything else.
At least when coils were coils.  :)
---------------------------
Mr. P.V.'d
formerly Droll Troll
> Thanks for all the advice.  I probably won't bother to do it when I
> change the oil.  I'd fill the oil filter with oil if I could, but in
[quoted text clipped - 14 lines]
>
> Phil
pcalvert@rocketmail.com - 30 Jul 2005 21:01 GMT
> If you disconnect the 12V wires going to the coil, you shouldn't have to do
> anything else.
> At least when coils were coils.  :)
> ---------------------------
> Mr. P.V.'d
> formerly Droll Troll

You are most likely correct.  But since disconnecting the wire carrying
the high voltage from the coil to the distributor is so easy, I figured
I'd go ahead and do that too.  Besides, the guys at the Department of
Redundancy Dept. think it's a great idea.  :-)

Phil
Sam Nickaby - 30 Jul 2005 06:22 GMT
<pcalvert@rocketmail.com> wrote in message
> Would it be okay to crank the engine for about thirty seconds with the
> coil completely disconnected?  By "completely," I mean that I will pull
> off the heavy-duty wire that goes to the distributor *and* I will
> disconnect the wires that supply the 12V to the coil's primary side.

A fuel pump fuse would be easier.
pcalvert@rocketmail.com - 30 Jul 2005 20:41 GMT
> <pcalvert@rocketmail.com> wrote in message
> > Would it be okay to crank the engine for about thirty seconds with the
[quoted text clipped - 3 lines]
>
> A fuel pump fuse would be easier.

Hi Sam,

Thanks for the suggestion.  I like that idea.  I think that should work
on fuel-injected vehicles, but I don't know if it would always work on
those that have a carb.  Depending on how long the engine has been
sitting, there might be enough fuel left in the carb for the engine to
start briefly before conking out.  If the engine has been sitting for a
year, though, I would think that it ought to work fine.

Phil
Sam Nickaby - 30 Jul 2005 23:00 GMT
> Hi Sam,
> Thanks for the suggestion.  I like that idea.  I think that should work
[quoted text clipped - 3 lines]
> start briefly before conking out.  If the engine has been sitting for a
> year, though, I would think that it ought to work fine.

Some carberaters have an electronic fuel cutoff valve. I've found that
cranking with the fuel supply on tend to destroy a spark plug. But, my
Honda service manual simply ask that I ground the high voltage line
(secondary) anyway.

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